Derivative Financial Instruments Cross Currency Swap (Details) $ in Thousands, € in Millions, AUD in Millions		3 Months Ended		9 Months Ended
	Dec. 22, 2016 AUD	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 22, 2016 EUR (€)	Dec. 01, 2016 AUD	Dec. 01, 2016 EUR (€)
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ (2,729)	$ 0	$ (6,397)	$ 0
Currency Swap [Member]
Derivative [Line Items]
Expiration Date		Jun. 30, 2019
Currency Swap 1 [Member]
Derivative [Line Items]
Notional Amount	AUD 123.9					€ 85.5
Currency Swap 2 [Member]
Derivative [Line Items]
Notional Amount	AUD 125.0					€ 86.3
BBR Interest rate [Member] | Currency Swap 1 [Member]
Derivative [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
BBR Interest rate [Member] | Currency Swap 2 [Member]
Derivative [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
EURIBOR Interest Rate [Member] | Currency Swap 1 [Member]
Derivative [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.68%
EURIBOR Interest Rate [Member] | Currency Swap 2 [Member]
Derivative [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.90%
Intercompany GRail Loan [Member]
Derivative [Line Items]
Debt Instrument, Face Amount							AUD 248.9	€ 171.7
Interest Expense [Member] | Currency Swap [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		$ (1,887)	0	(1,887)	0
Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Net of Foreign Currency Transaction Gain (Loss) on Intercompany Loan		$ (842)	$ 0	$ (4,510)	$ 0